A conveyor belt is used for transportation of materials and the like, and as the transportation volume increases, demands in improvement in durability (tear resistance, bending resistance and the like) have increased in recent years.
Meanwhile, in order to improve transportation efficiency, a conveyor belt as long as several kilometers in length is also introduced in the market. Accordingly, the power consumption is also increasing. Therefore, a conveyor system with good energy-saving properties is also in demand. Furthermore, there is an increase in demand for a conveyor belt in cold regions. Thus, good energy-saving properties are also required at low temperatures, such as approximately −40° C. That is, good energy-saving properties are required for a wide range of temperatures (for example, −40 to 20° C.).
As a rubber composition used for production of a conveyor belt, Japanese Unexamined Patent Application Publication No. 2008-38133A discloses “a rubber composition for a conveyor belt comprising a rubber component including a natural rubber (NR) and a poly-butadiene rubber (BR), a carbon black and the like”. In addition, Japanese Unexamined Patent Application Publication No. 2008-38133A discloses that energy consumption can be reduced by using such a rubber composition for a conveyor belt.
Under these circumstances, the present inventors have studied a rubber composition for a conveyor belt containing a natural rubber, a butadiene rubber and a carbon black using Japanese Unexamined Patent Application Publication No. 2008-38133A as a reference. The study lead the present inventors to realize that energy-saving properties, tear resistance, and bending resistance of the conveyor belt obtained requires further improvement considering the increased level of demand for the future transportation efficiency and durability.